International Excursion in America. 331 
the swamp is now mostly occupied by an association of various 
species of Carex, including C. filiformis and C. Psendocyper us, which 
are dominant. These are developed on a floating layer of peat 
through which rise numerous shoots of Scirpus lacustris and Typha 
lalifolia, with here and there Phragmites communis and Cladium 
mariscoides, relicts of the former reed-swamp. Lastrea Thelypteris 
is very abundant on the peat, which has many of the characteristics 
of English fen. In places, however, bog plants such as Sarracenia, 
Drosera and others occur. A phase of shrubs ( Salix Candida, Rhus 
vernix, Betula pumila, Rhamnus alnifolia, etc.) leads on to the close 
canopy tamarack wood of Larix laricina and Betula lutea with Acer 
rubrum,Nyssasylvatica, etc., and on the ground Osmunda cinnamomea, 
0. regalis, Mitchella repens, Coptis trifolia, Trientalis americana, etc. 
This succession appeared to the European botanists to be 
essentially of the “ Niedermoor ” or fen type, with local tendencies 
only to develop a “ Hochmoor ” vegetation, as was seen in a neigh¬ 
bouring hollow dominated by Chamcedaphne. From descriptions 
however it would appear that some if not all of the more northern 
tamarack swamps arise from a “ Hochmoor ” succession. 
Chicago Prairie. 
The Chicago region, as has been said, is naturally a region of 
mixed forest and prairie. To the east the eastern climax (beech- 
maple) type of forest predominated: to the west the prairie areas 
gradually increase, and the forest areas (oak-hickory type) decrease. 
The prairie shows several more or less distinct types, such as low 
prairie, blacksoil prairie, sand prairie and so on. Low prairie is 
clearly, in this region at least, a natural succession from lake and 
marsh or fen. Good transitional stages between fen and low 
prairie may be observed close to Chicago in the vicinity of Wolf 
Lake, and low prairie still exists within the city limits at Chicago 
Lawn. This contains, however, a good many species said to be 
typical of high prarie. Thus it is largely dominated by Agrostis 
with the ubiquitous Poa pratensis (called in America “ Kentucky 
blue-grass”) Hordeum jubatum, and Elymns canadensis. Among 
the species which clearly show the origin from fen and which are 
familiar to the European botanist are Lathyrus palustris and 
Stachys palustris; while Spartina cynosuroides, Calamagrostis 
canadensis and Muhlenbergia racemosa are low prairie grasses. 
Mixed with these are numerous Composites: Liatris spicata, Aster 
multiflorus, Solidago rigida and canadensis, Erigeron ramosus, 
